The invention relates to an electromagnetic relay comprising a divided housing consisting essentially of a flat part and of a cap-shaped part which are bonded to one another in such a way that a circumferential groove on the inside of the one part is filled with an adhesive in which the rim portion of the respective other part immerses.
Electromagnetic relays, in particular such ones which are intended to be soldered on to printed circuit boards, are required to have a completely tight relay housing, i.e., a housing which is at least wash-tight, preventing soldering vapours from entering into the interior of the relay housing while soldering the terminals of the relay to the printed circuit board, as well as for preventing liquids from entering into the relay housing during the subsequent cleaning of the printed circuit board by using various washing liquids.
Housings of electromagnetic relays chiefly have leakages at two points, i.e., at the points where the two parts of the housing are connected and at the points where the terminals are led through the housing.
For sealing the lead-through points of the electric terminals it is already known from DE-OS No. 2,129,918 to seal the relay housing at the lead-through point with a foil through which the electric terminals project. In particular, there is suggested to use a foil of thermoplastic material which, by the effects of heat, is supposed to be bonded to the terminal pins. This foil may also be of trough-shaped design in order to simultaneously protect the connecting points between the individual parts of the housing.
Such a measure is not only expensive and circumstantial, but also unsuitable for obtaining a wash tight sealing of the relay.
Likewise expensive is the measure as disclosed in DE-AS No. 2 616 299, i.e., of depositing a covering layer of a material having a high capillary absorptive capacity, on to the housing especially at the points where the terminals are led through, and to saturate this material with a highly fluid sealing compound.
Finally, from DE-OS No. 2 851 329 it is known to seal the lead through points of the terminals in the bottom of a relay by a synthetic resin compound deposited from the outside. This conventional measure is likely to cause elevations on the bottom of the relay, owing to the sealing compound, preventing the relay from being correctly placed on to a printed circuit board. Moreover, there is still required an additional sealing of the individual parts of the housing.
From DE-OS No. 2 622 133 it is still known to effect the sealing of the interlockingly engaging parts of the housing of an electromagnetic relay in such a way that a sealing compound is inserted between the interlocking parts of the housing. This is intended to create a large sealing surface between the parts of the housing. This, however, not only requires housing parts which fit exactly on to each other, but also the insertion of the sealing compound during the assembly is circumstantial and rather time consuming. Moreover, the large joining surfaces also require greater amounts of sealing compound.
In this conventional type of embodiment it is also possible to lead the electric terminals between the two parts of the housing, towards the outside. This not only requires a complicated form of terminals, but also requires a still larger amount of sealing means between the two parts of the housing, because these, owing to the terminals led therethrough, are compulsorily also held at a relatively large spacing.
Finally, from DE-GM No. 8 020 770 there is known a housing for an electromagnetic relay which consists of a trough-shaped base and of a cover placed thereon. The cover is provided with a circumferential groove which is filled with a suitable adhesive in which the rim portion of the trough-shaped housing member is immersed. In this way there is achieved a simple bonding between the parts of the housing. The electric terminals of the relay are led through the bottom part of the trough-shaped housing member and, therefore, must be provided with a separate sealing.
The invention is based on the prior art according to DE-GM No. 8 020 770.
It is the object of the invention to achieve in a simple way and with a small amount of sealing material, a simultaneous sealing of the housing members with respect to one another and of the points at which the terminals are led through the housing.